Tunnel portal construction



June 23, 1953 W. E. ANDREWS m PORTAL cons'muc'rrou v 6 Sheets-Sheet 1Filed April 21, 1948 JNVEN TOR. W. EARLE. ANDREWS HIS A TTORNEY.

8. S 8 2 &W H a mu 2 e m0 M M m N T H 2 m .n R 5 s 6 m 4 l// w.

W E ANDREWS TUNNEL PORTAL CONSTRUCTION June 23, 1953 Filed April 21,1948 6 SheetsF-Sheet 3 mmvrox. w. EARLE ANDREWS BY H/5 ATTORNEK June 23,1953 w. E. ANDREW? TUNNEL PORTAL CONSTRUCTION Filed April 21, 1948 June23, 1953 I w. E. ANDREWS 2,642,788

TUNNEL PORTAL CONSTRUCTION Filed April 21, 1948 6 Sheets-Sheet 5 2soo-2000- AVERAGE DAYLIG'HT FOR LoIvcEsr DAY (JUNE 2/) I x \\/I I F|G.7.[500- YEARLY AVERAGE CONTINUED THROUGH 33 TUNNEL s FOOT CANDLES \I Q l 2I 5 EXTRA LIGHT FIXTURES I k m CONTINUED rmzoucn o TUNNEL 5 FOOT cANoLEsI E I I 2 w z I I k GRADUATION OF I z DAYLIGHT UNDER I 2 CANOPIES l v IEXTRA ARTIFICIAL I AVERAGE DAYLIGHT I FOR SHORTEST DAY LIGHT AT PORTAL[TUNNEL END OF (DECEMBER 21) I UNIFORM FULL I I I ARTIFICIAL oA LIcHT---\1 ,11 I LIGHT 1 I I o I I I I I I I I I I l I I I I I I T I I I T II i 0 50 I00 3a 150 200 250 DISTANCE IN FEET l3 5 FOOT CA NDLES F l I INVENTOR.

W. EARLE ANDREWS HIS ATTORNEY.

June 23, 1953 w. E. ANDREWS 2,642,788

' TUNNEL PORTAL CONSTRUCTION Filed April 21, 1948 .6 Sheets-Sheet 6AVERAGE DA'YLICH'T FOR LONGEST DAY 2 50o- (Ju /vs 21) -\--T;\ I I: DZ 1I l 2000- i l l FIG.9.

l YEARLY AVERAGE I [500 DAYL/CHT f3 r \l I Q i z I EXTRALIGHT FIXTURES 3i 75 FOOT cANouzs k I000- I MAX/MUM I 8 l I: IL I z I PORTAL I; F w SAVERAGE DAYLIGHT E I g?:%: 1 2 FOR SHORTEST DAY i I END OF (DECFMBER 2/)1 EXTRA ARTIFICIAL LIGHT:

/z E AT PORTAL 75 FOOT CANDLES DAYLIGHL 1 I 1 Y mi 0 I I I I I I I I I II I I I I I I 1 I I I I DISTANCE IN FEET 5 07 D Es F'IG.|O..

JNVENTORQ w. EARLE ANDREWS Hi5 A TTORNEX Patented June 23, 1953 UNITED 1STATES PATENT OFFICE n 2,642,788 I TUNNEL PORTAL CONSTRUCTION WilliamEarleAndrews, NewYorhN. Application April 2 1, 1948, Serial No. 22,417 g1 This invention relates to a tunnel construction; more particularly toa portal approach f or tunnels; and still more particularly to theilluminating f atures of the approach to a tunnel portal.

Itis an object of my invention to minimize the human hazard involved inaccommodation of the eyes in the transition in passing from a high levelof illumination to a point having a low level of illumination, such asis involved in entering the portal of a tunnel during daylight, to thelow level illumination of the'tunnel furnished by artificialillumination. My invention is concerned with the provision of a portalconstruction for tunnels, joining roadways or railway right-of-ways andwhich are entered by vehicles at relatively high speeds from apointhaving.

involved in effecting a transition from the high level value to the lowlevel values abruptly or within a time factor which would involve a lagin eye accommodation, with its consequent hazard.

Still more particularly, it is an object of my invention to provide. acanopy construction for the entrance portal of tunnels to shield theroadway from illumination gradually, so that the eye may accommodateitself in passing into the tunnel with its relatively low levelillumination factors, without hazard by reason of momentary loss ofVisibility. 7 I To attain these objects and such further objects as mayappear herein, or be hereinafter pointed out, I make reference to theaccompanying drawing forming a part hereof, in which Figure 1 is a planview of a roadway construction including tunnel approaches and portalsillustrating my invention;

Figure 2 is a magnified section taken on the line 2-2 of Figure 1; n

Figure 3 is a plan view of a canopy at a portal;

Figure 4 is a side elevation taken on the line 4-4 of Figure 3-; I

Figure 5 is a section taken on the line 5-5 of Figure 3;

Figure 6 is a fragmentary plan view of the portal construction andcanopy, with illustration of supplementary illumination; 3

Figure 7 is a diagrammatic chart illustrating the relationship of lightvalues todistance 2 Claims. (Cl. 94 -1 traversed in a canopy to a tunnelportal in accordance with my invention;

Figure 8 is a perspective view of the tunnel portal and adjacent area toprovide visually the representation of the coordinate factors of thechart;

Figure 9 is a diagram chart illustrating the relationship of lightvalues to distance traversed in'a portal construction in accordance withexisting tunnel portals and adjacent areas;

Figure 10 is a perspective view' of the portal and adjacent'area toprovide visually the representation of the coordinate factors of thechart. Making reference to the drawing, there is illustrated a roadwayconstruction wherein a tunnel i0 is intended to join roadways H and I2to have the respective portals l3 and i4 thereof adjacent an areasubject to ordinary daylight illumination. In accordance with theexemplification, the portals! 3 and Hi include entrance ramps [5 and i6and exit ramps H and I3,

descending from the level of the roadways l l and V I2. Each of theportals l3 and M has side walls I9, 20, and 2 I, 22, respectively, withdivision walls 23 and 24, respectively, separating the roadways [5, ifand I6, I8, at the portals I3 and i4. Coping.

25, 26, 21, 28 overlies the wall structure extendingabove the roadwaysabove the portals.

Each of the entrance roadways l5 and i6 is provided with a canopy 29 and30-, respectively,

comprising angularly edged segments 3| and 32 overhanging the roadwayfrom the crotch 33 to the points of the branches 34, 35, which mergeinto the walls l9 and 23, respectively, providing between the segments3| and 32 a skylight 36 which graduates in outline from points 34, 35 tothe crotch 33, previously described. W

The adjacent entrance portal area constituting the walls I9, 23, thesegments 3| and 32, have facing 3T of material with due regard to itslight reflectance value as well as to the structural requirements in thetunnel zone. The ceiling of-the segments 3| and 32 may likewise befinished with facing material 38, such as tile, to

augment or qualify the light reflectance value of the adjacent area,whether by daylight illumination or augmented by artificialillumination, as will appear moreclearly hereafter.

The extensiveness of the ramp and the canopied section adjacent theentrance portal to secure the reduction inhazard as contemplated by meis 'a factor of width of roadway, allowable speed of traflic, height ofthe vertical-walls to the ramp, as well as adjacent terrain. In general,however, I have found that with a roadway of approximately twenty ninefeet, with a canopy which graduates from full opening to the crotch inabout one hundred sixty feet, that an apron of about forty feetto theportal opening exemplifies a type of graduation of illumination whichmakes the transition from the level of 3 illumination experienced indaylight to the illumination by artificial light within the tunnel toaccommodate the eye to the transition, without loss of visualefficiency, and permitting unretarded movement of traflic from the high.level light intensity to the low level light intensity.

It is contemplated by a more particular phase of my invention also tosupplement the illumination adjacent the portal with artificial sourcesof light. In Figure 6 I have illustrated a fragmentary portion of theportal including the canopy wherein a series of light sources Lbeginning from beneath the canopy segments 31 and 32 and to and withinthe tunnel 10 are strung along at varying distances from each other,being more sparsely located at and adjacent the crotch, moreconcentrated from this point to adjacent the tunnel as the portalaperture is entered, and then uniformly spaced within the tunnel zone.

In Figures 7 to 10 I have graphically illustrated the relative value ofa tunnel portal constructed in accordance with my invention as comparedwith existing installations known to me, plotting average foot candlesagainst distance, in which the ordinate axis is plotted in foot candlesand the abscissa in distance corresponding to feet.

Figure 8 schematically superimposed the entrance roadway covered by thecanopy in accordance with my invention up to the portal and a shortdistance from the portal into the tunnel. In the chart there is plottedfoot candles experienced from the extreme condition, i. e. averagedaylight for the longest day of the year, June 21st, curve I; and forthe shortest day of the year, December 21st, curve H; and the yearlyaverage daylight, curve III. The curves taper to the constant which maybe maintained within the tunnel in of approximately foot candles, as maybe maintained by the artificial light uniformly maintained in the tunnelitself. A segment IIIa diverts from the curve III to the extent thatextra artificial light is added adjacent the portal in accordance withthe embodiment illustrated in Figure 6 and as above noted may beeffected in varying concentrations.

In general, it will be observed that the light values in foot candles ofmeasurement graduate from the daylight intensityto the low levelintensity of the tunnel of 5 foot candles within the distance of abouttwo hundred and fifty feet without any abrupt change.

In Figures 9 and 10 there is plotted'a relationship of light in footcandles in the ordinate-to distance in the abscissa under conditionsemploying nothing more than the graduated wall from the roadway leveladjacent the ramp to the portal. Curve IV plots the change for averagedaylight for the longest day of the year; curve V shows the light valuesagainst distance for average daylight for the shortest day of the year;curve VI shows the light values plotted against distance for the yearlyaverage daylight. Segment We of curve VI departs from the normal curveVI where the portal illumination is augmented by additional artificiallight of approximately 75 foot candles.

It will be apparent from a comparison of the charts that the transitionfrom maximum illumination to minimum illumination in the case of theconstruction illustrated in Figure 10 is of the order of from ten tothirty feet whereas in accordance with the construction shown in Figure8, the graduation of light 'under the canopies is accomplished in adistance of almost one '4 hundred seventy five feet. The eye thereforehas more than four times the time element to accommodate itself to thetransition in light intensity.

It will be observed that while in the construction which I have providedand which includes at the approach to the portal, a down grade ramppartially shielded by the walls which are provided by combining with aroadway of approximately thirty feet in width, canopy segments whichconverge within a distance of approximately one hundred sixty feet fromthe apex to the crotch, it will be understood that where the tunnelportal is on a level with the approach or is reached by an ascent in theapproach, the support for the canopy and the convergence of the canopysegments may require modification, in accordance with the existingterrain.

While I may, by my construction, as above stated, augment the naturaldaylight illumination adjacent the portal, the uniform graduation inlight intensity in accordance with my construction requires the use offewer extra fixtures at the portals than would be involved ifcompensation for lack of fast accommodation of the eyes is endeavored tobe made at a point inwardly spaced from the portal, thereby effectingvery substantial installation economies.

Under the construction in accordance with'my invention, traffic mayproceed at unretarded speeds without hazard as there is no requirementto reduce speed in approaching the artificial illumination of the lowmagnitude maintained within the tunnel after passing the portal.

Having thus described my invention and illustrated its use, what I claimas new and desire to secure by Letters Patent, is:

1. An entrance roadway leading to a tunnel portal comprising supportsalong said roadway leading to said portal, a canopy partially overlyingsaid entrance roadway and tapering from the sides of said supports at adistance of approximately two hundred feet to a point over said roadwayapproximately forty feet from said portal, to form a V-shaped notch insaid canopy exposed to daylight, to reduce natural illumination wherebyin approaching and entering said portal at the rate of movement rangingapproximately from fifteen to sixty six feet per second, over saiddistance hazards involved in lag in human eye accommodation areovercome.

2. An entrance roadway leading to a tunnel portal comprising side wallsleading to said portal, a canopy partially overlying said roadway andtapering from each of said side walls at a. distance of approximatelytwo hundred feet to a point over said roadway approximately forty feetfrom said portal to form a V-shaped notch in said canopy exposed todaylight to reduce natural illumination whereby, in approaching andentering said portal at a rate of movement ranging approximately fromfifteen to sixty six feet per second over said distance, hazards in lagin the human eye accommodation are overcome.

W. EARLE ANDREWS.

References Cited in the file of this patent UNITED STATES PATENTS NameDate Skultin Oct. 23, 1928 Number

